The present invention relates to improved means for supporting large masses such as cyclones and plenum chambers within a vessel which is subjected to relatively high temperature differentials which cause both vertical and horizontal thermal expansions. In particular, certain pressure vessels in petroleum refineries, such as in a reactor or a regenerator of a catalytic cracker, contain plenum chambers connected to centrifugal separators (i.e. cyclones) to separate the solid catalyst particles from gases flowing upwardly within the vessel. In most of these cases, numerous cyclones are employed usually arranged in two concentric rings of cyclones wherein a ring of primary cyclones is connected in series with a ring of secondary cyclones. Dirty gases enter the primary cyclone ring from the pressure within the vessel, pass through the two cyclones in series and the cleaned gases discharge from the secondary cyclone outlet into a collector or plenum chamber. This collector or plenum is contained within the main vessel and in the prior art, such as in U.S. Pat. No. 4,273,565, it has been conventional to have its upper surface provided by the vessel head. Typically, the plenum chambers and cyclones operate at elevated temperatures of between 1200.degree. F. and 1800.degree. F. These elevated temperatures require the vessel to be internally insulated and also require the use of high alloy steels for the fabrication of the plenum and cyclones, but even then, allowable stresses in the steel components are very low, requiring efficient load transfer to prevent failure of the steel components. Additionally, large differential movements result, sometimes as much as three to four inches between the hot inner parts within the vessel and the relatively cold internally insulated outer shell. Because these process vessels also usually operate at elevated pressure, they require careful design to retain a pressure seal between the inlet and outlet sides of the cyclone system and between the cyclone system and the plenum chamber.
Typical of the aforementioned described prior art arrangements are illustrated in U.S. Pat. No. 4,273,565, and U.S. Pat. No. 2,728,642. In systems of this type illustrated by these representative prior art patents, the large expansion rate of the alloy steels used in the components at elevated temperatures results in significant differential horizontal (radial) and vertical expansions between the hot internal cyclone and plenum parts and the colder vessel shell to which these parts are directly secured. Support of the cyclone system is further complicated by the movement of the plenum relative to the vessel shell when these cyclones are fixedly supported from the cold shell relative to the moving hot plenum members. Since the plenum must be totally isolated from the cyclone inlet side of the vessel to prevent flow bypassing around the cyclones, a rigid connection from the plenum to the shell is required. However, such connection is subject to stress because of the differential thermal expansion rates of all these rigidly connected parts, and accordingly failure due to stress concentrations is sometimes experienced. This occasional failure can be appreciated since typically the total weight of the cyclone system within a catalytic cracker vessel is several times the weight of the associated plenum and may be as much as 400 tons total weight. The problem of load transfer of this suspended mass to the main vessel shell is particularly critical at the elevated temperatures encountered within the operating environment which severely reduces the permissible stress on the high alloy steels employed.